Unfortunately the last 2 updates (patch 160 and patch 161) both broke mkv support (see previous posts). After 160 I was able to receive a file from Arcsoft Support (uMediaClub.dll), that fixed it. I do not have any update on how to fix patch 161.
My TMT 3 Platinum (with SimHD) now works after going back to build 160 with the uMediaclub.dll fix. It plays all the mkvs I throw at it.
I suggest you contact support directly and ask for help. If they send you the 160 patch and the dll, you can get going.
I have become very careful with TMT upgrades - their quality assurance has opportunities for improvement......
Other than that great software (for what it's worth).